Time dependent 3D Maxwell material viscoelastic Earth deformation

Numerical methods and mathematical models of Elmer
fpk
Posts: 10
Joined: 31 Jul 2020, 11:36
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by fpk »

Gents,
with your help i've built required multibody mesh with single (conformal) surface boundary between bodies, thanks for help and teaching!
Actually, i want use as loading top boundary surface not flat surface but the surface which close to the real sea bottom bathymetry (the image and cross-section find please attached). First attempt was not successful, look's like "Normal force" is not applicable for not flat boundary surface. Could you advice how to load such kind of boundary?
Thanks in advance!
Attachments
multibody.png
(82.09 KiB) Not downloaded yet
top_surface.png
(122.67 KiB) Not downloaded yet
crossect.png
(11.96 KiB) Not downloaded yet
kevinarden
Posts: 2237
Joined: 25 Jan 2019, 01:28
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by kevinarden »

I believe these are your options for boundary forces
loads.png
(28.54 KiB) Not downloaded yet
fpk
Posts: 10
Joined: 31 Jul 2020, 11:36
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by fpk »

Kevin, thank you for support,

then i've met iterations problem.

My machine is AMD Ryzen7 2700 eight core processor x16, Memory 32CiB, Ubuntu 20.04 2LTS 64bit.
After several efforts i found configuration:
Linear System Solver = Iterative
Linear System Iterative Method = GCR
Linear System Max Iterations = 3000
Linear System Preconditioning = BILU2
Linear System Convergence Tolerance = 0.001
which promised only several days to compute 21000 years of forcing to the sea bottom by water layer which increasing from 0 to 120 m of depth during that time.

Could somebody of society advise how estimate convergence tolerance if i want error of z-displacement not more than 1 cm? and determine how long time require calculate it.

Sincerely thanks
in advance.
Attachments
deform.png
deform.png (17.5 KiB) Viewed 2145 times
raback
Site Admin
Posts: 4812
Joined: 22 Aug 2009, 11:57
Antispam: Yes
Location: Espoo, Finland
Contact:

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by raback »

Hi

For standard elasticity I would recommend linear solver in style:
https://github.com/ElmerCSC/elmerfem/tr ... StabBoomer

But here it seems that you also solve for the pressure. What kind of block is the (4,4) block? Are the bubble degrees of freedom condensed away from the linear system?

The optimal strategy could be some kind of block preconditioning strategy. Like for the Stokes equation the system may be preconditioned such that using the true blocks for the velocity but an rough approximation of the schur complement for the pressure block (scaled mass matrix). This could be something similar but I'm not too familiar.

-Peter
kevinarden
Posts: 2237
Joined: 25 Jan 2019, 01:28
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by kevinarden »

A posting of the log file from the run my help provide some insight.
fpk
Posts: 10
Joined: 31 Jul 2020, 11:36
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by fpk »

find please attached - sif, top part of the log and Lua
Attachments
depthload.txt
(471 Bytes) Downloaded 128 times
case.sif
(5.7 KiB) Downloaded 128 times
current_sollog.txt
(253.24 KiB) Downloaded 123 times
fpk
Posts: 10
Joined: 31 Jul 2020, 11:36
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by fpk »

raback wrote: 05 Oct 2021, 17:44 Hi

For standard elasticity I would recommend linear solver in style:
https://github.com/ElmerCSC/elmerfem/tr ... StabBoomer

But here it seems that you also solve for the pressure. What kind of block is the (4,4) block? Are the bubble degrees of freedom condensed away from the linear system?

The optimal strategy could be some kind of block preconditioning strategy. Like for the Stokes equation the system may be preconditioned such that using the true blocks for the velocity but an rough approximation of the schur complement for the pressure block (scaled mass matrix). This could be something similar but I'm not too familiar.

-Peter
Peter, thank you for recommendations,

sorry if i miss understood somethings,
i believe, i am using next applications described by:
Chapter6.2.2 from
https://www.nic.funet.fi/pub/sci/physic ... Manual.pdf
and paper
https://doi.org/10.5194/gmd-13-1155-2020
so, pressure is mandatory. Also, i do not use any stabilization techniques, look's like i need involve them?
i am a not good skilled beginner for Elmer, could you explain more detail for your question "What kind of block is the (4,4) block?"

Sincerely
kevinarden
Posts: 2237
Joined: 25 Jan 2019, 01:28
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by kevinarden »

Youngs Modulus = 6.5844e+11
Viscosity = 2.7E+21

These are large numbers even for a 64 bit double precision computer. The problem is these values are divided by, use to divide, possibly very small numbers. Even though the 64b dp might be able to handle it it severely impacts the precision of the result, you start losing accuracy to the first decimal place. This potential accuracy issue could cause convergence issues.
tzwinger
Site Admin
Posts: 99
Joined: 24 Aug 2009, 12:20
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by tzwinger »

Hello,

If it helps, please find attached a similar case like the 2D test-case in 3D (runs on my gaming PC with 16 GB RAM and 6 core i5). Picture shows timestep of max. deformation:
deformation.0099.jpeg
(54.4 KiB) Not downloaded yet
Mind, to first create mesh-file (keeping in mind, that one has to move from kilometres to metres):

Code: Select all

gmsh -3 duallayer3d.geo
ElmerGrid 14 2 duallayer3d.msh -autoclean -scale 1000 1000 1000 
ElmerGrid 2 2 duallayer3d -partdual -metiskway 6
(mind, my computer has 6 cores, change the last number accordingly to your hardware)

Best wishes,
Thomas
Attachments
duallayer3d.tgz
(2.59 KiB) Downloaded 136 times
annier
Posts: 1168
Joined: 27 Aug 2013, 13:51
Antispam: Yes

Re: Time dependent 3D Maxwell material viscoelastic Earth deformation

Post by annier »

Thomas,
Thank you for the test example. Especially, it is helpful for us to make comparisons between MATC and lua style expressions for writing functions.

Yours Sincerely,
Anil
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Post Reply